Phenol formaldesyde-rye flour-sodium hydrosulfite containing adhesive composition



Patented Jan. 1, 1 952 UNITED STATES PATENT OFFICE PHENOLFORMALDEHYDEJEYE FLOUR-SO- DIUM HYDROSULFITE CONTAINING AD- HESIVECOMPOSITION g Laurence E. Clark, J r., Bainbridge,.N. Y., assignor toThe Borden Company, New York, N. Y.,

corporation of New Jersey No Drawing- Application April 15, 1947,

' p Serial No. 741,688

This invention relates to synthetic;;res in compositions, and inparticular-to condensation-type resin adhesives which are: combined withseed 'flour extenders. I I,

Heretofore, it has beenfound desirable to employ gluten-containing seed.flours as extenders for condensation type resin adhesives. Suchextenders are used primarily to reduce costs. An

aqueous medium, such as water, is always a necessary ingredient when anextender of the class described is used .in combination with theaforesaid condensation-type resin adhesive as, for example, when theadhesive is spread over a surface to be glued or assembled. When suchgluten-containing seed flours are used as extenders the amount of waterrequired for the mix depends primarily upon the'quality of theparticular seed flour used. Poorer grades of seed floursrequire morewater than the better grades.

In such practice, however. serious problems have arisen because, whensuch extenders have been used in substantial amounts, the free .flo'w ofthe resin composition is retarded and the liquid adhesive is thus foundto be spreadable only with difiiculty. Such compositions hecome stringyand have a porridge-like consistency on being dissolved or dispersed inwater. In addition, such resin adhesives, when highly extended with agluten-containing seed flour, inevitably require the addition ,of'largequantities of water to enable them to become spreadable. This raisesfurther problems, however, in that when such large amounts of water areused various difiiculties arise in the subsequent processin operationsas, for example, when these adhesives are employedin wood laminating inhotpressing operations. The large amount ofwater employedis-convertedinto steam-during thehotpressing operations whichin turncauses the formation' of blisters between the laminae, thus making thefinished article unfit for commercial 1186.

It. was, therefore, a general object of this invention to overcome thedisadvantages heretofore encountered, and to improve the spreadingproperties and characteristics of condensationtype resin adhesivecompositions employin seed flour. extenders.

Another object of this inventionv was to reduce-the amount .ofwaterrequiredto produce an adhesive composition of a resin and seedflour combination.

i Claim. (01. 260-4) Still another object of'this invention was to andwhich would have other desirable properties when used in hot-pressingoperations. F'urther objects of the invention Will'be appa entfrom thefollowin specification and ,claim.

Accordingly, I have now overcome the foregoing difiiculties and haveachieved the aforesaid objects by combining the synthetic resin adhesiveof the class described with a chemicallyrnodified gluten-containing seedflour extender. The seed flour extender is modified by chemicaltreatment of the gluten ontained in the hour,

and such extender, when combined with the aforesaid resins, yields afree-flowing and easily time still have sufficient water present to givea satisfactory wet mix adhesive having good spreading characteristics;and vmoreover, when the modified seed flour is employed, the amount ofwater which is necessary to give a satisfactory mix is less than thatamount required when an unmodified seed flour. is employed. For example,when a chemically-modified seed flour was employed as an extender incombination with a condensation-type adhesive of the class de scribed,the amount -of water necessary to pro- .videa satisfactory adhesivecomposition was re.- duced by approximately 10 per cent.

Gluten-containing seed hours in general are suitable for use in. thepractice of this invention. Examples .of such seed flours comprise thosederivedfrom wheat, rye, sorghum, and the like. Rye flour ordinarilyrequires, more water than wheat flour but the rye flour may be'chemically modified or thinned by treatment in the same manner as'wheator any other gluten-containing flour.

Gluten is a water-insoluble protein. It isbelieved that the gluten formsa colloidal suspension in anadhesive composition mix, upon the additionof water or other aqueous media, and it is chiefiybecause of thisphysical characteristicthat such'resin adhesive compositions con tainingasubstantial amount of -glutencontaining-seed flour exhibit a thickenineffect when water is present. If the gluten is removed or modified,however, the starch contained in the seedfiour disperses in aqueousmediato'a certain extent without unduly --thickeningand with out producingmixes having undesirable stringiness which impairs itsspreadlngtproperties.

Sulfur dioxide gas (S02), an aqueous solution of the gas, e. g., H2S03,and a substance which may be decomposed to release S02 or H2503 arethose chemicals which may be employed in the present invention tomodiiy. the gluten in the seed flour. For purposes of definition, theterm SOz-producing substance as used herein, therefore, is intended toinclude such chemicals.

Broadly, the gluten-containing seed flour may be modified by treatmentwith an SOz-producing substance; in particular, sulfurous acid, H2S02.The H2803 used for such purposes may be acquired in various ways. Forexample: sulfur dioxide gas may be passed into an aqueous media to form.H2503, and the flour mixed therewith, or the flour may be premixed withthe aqueous media prior to introducing the S02 gas, or the S02 gas maybe passed into an aqueous flourresin adhesive mixture. The H2803chemically reacts with the gluten of the flour, and the flour is thusmodified for the purpose of making it satisfactory for use as anextender. Instead of ,using sulfur dioxide gas or sulfurous acid, theremay be employed a substance which upon being dissolved in aqueous mediaand/or heated decomposes to release S02 gas or HzSOs.

An soz-producing substance, e.g., sulfur dioxide, sulfurous acid or asubstance decomposable to S02 or H2803 may be added to a resinadhesiveflour mixture. In the case of a substance decomposable to S02, suchsubstance may be added to the flour, the resin adhesive or to ..theadhesive-flour mixture and the S02 then gradually released through theaddition of water, with or without heat.

Alternatively, a master-mix may be made of the flour extender, water anda substance which decomposes to S02 or HzSOs, preferably upon slightheating, such as sodium metabisulfite. 'After modification of the glutenin the flour has taken place, a dry-resin adhesive in powder form may beadded thereto, or a portion of the modified gluten flour extenderfromthe master-mix may be added to a dry-resin adhesive in powder formtogether with water sufficient to dissolve the resin powder.Alternatively, the modified gluten-flour extender from the master-mixmay be added to a liquid resin in place of a resin powder.

As a further alternative, there may be employed a flour which has beenpremodified by an S02 treatment as, for example, in accordance with theteachings of U. S. 1,969,347 to Bauer, and such flour then used as anextender for the resins of the class described. The SOzreactschemicallywith the flour and has a degelling action on the gluten in the flour,preventing the formation of dough or gel in the presence of moisture orwhen the flour is moistened with water.

In the now preferred embodiment, the S02 may be released in situ byadding an acid-producing salt together with a salt, which decom- -posesto release S02, to a mixture of the resin and extender and thereafterthe S02 is released by hydrolysis when water is added to the mixture.For example, the S02 is released in situ by including anSOz-decomposable substance with most ordinary catalysts employed withthe acid curing resin adhesives, such as urea-formaldehyde, especiallywhere there is some free formaldehyde present. 'A typical catalyst foracidcuring resins of the class described is ammonium chloride, anacid-producing salt. It is thought that the ammonium chloride reactswith the free formaldehyde present in the resin to releasehydrochloric'acid and hexamethylenetetramine,

or an intermediate thereof. The hydrochloric acid in turn reacts withthe SOz-decomposabie substance of the class described to release sulfurdioxide, and the sulfur dioxide then reacts with thegluten contained inthe flour, producing a- 5 'bisulfite, which decomposes in aqueoussolution to'produce sulfur dioxide, which in turn produces the desiredthinning effect upon the gluten-containing flour. Addition compounds ofsulfurous acid and salts of sulfurous acid in general are satisfactorybecause they liberate sulfurous acid by hydrolysis. Addition compoundsof anhydrides of sulfurous acid and their salts, examples of which aresodium meta-bisulfites and sodium pyrosulfites, also producea goodthinning effect upon the flour in an adhesive mix. SOz-decomposingsubstances such as derivatives of sulfurous acid and salts thereof, forexample, sodium hydrosulfite, sodium thiosulfate, and the like, do notordinarily break down to release S0 in neutral solution. As a rule theremust be some acid present to decompose these substances to release theS02 by hydrolysis. Organic addition compounds of sodium hydrosulfitewith aldehydesand ketones, such as sodium formaldehyde sulfoxylate,readily yield S02 in the adhesive mix and hence, may be .used to modifythe gluten and thus produce a satisfactory thinning eifect.

The practice of this invention is particularly applicable to resin-seedflour mixes wherein the amount of seed flour extender used is greaterthan the amount of resin in the extended ad hesive composition, evenwhen the amount of extender is as much as 400 parts to parts of 62%solids of liquid resin. In general, how.- ever, improved spreadabilityof adhesive com.- positions containing seed flours is accomplished bythe addition of a thinningagent regardless of the extent to which theresin is extended, but it is not usually the practice to add a modifyingagent to an extended resin composition unless the amount of extender isat least equal to the amount of resin used.

In general, these extenders are'used with the condensation-type resinsto form the adhesive compositions such, for example, as urea-aldehyderesins, aniline-aldehyde resins, phenol-aldehyde resins,resorcinol-aldehyde resins, melamine-aldehyde resins, and the like.

Phenol-type bodies which may be used to pro:- pare condensation-typeresins comprise phenol, the ortho, meta, and para cresols, cresylicacid, xylenol, resorcinol, catechol, quinol (hydroquinone), pyrogallol(pyrogallic acid), phloroglucinol, or combinations thereof, and thelike. Amines, amides and triazines which may be used to prepare theaminoplast resins of the class described comprise urea, thiourea,guanidine, methyl urea, acetyl urea, cyanamide, dicyancdiamide, biuret,semi-carbazide, melamine, mono phenylmelamine, diphenylmelamine,triphenylmelamine, ammeline, thioammeline, ammelide. formoguanamine,acetoguanamine, lauroguan amine, stearoguanamine, and the like.

These aforesaid bodies or combinations thereof may be reacted with thevarious aldehydes, as a class, to produce the condensation-type resin ofthis invention, such, for example, with formaldehyde,-- acetaldehyde,propionaldehyde,

. 5i crotonaidehydeg; benzaldehyde,- furfuraldehyde; andith'ewlike:

In general, the acid-curing type resins; suchasz the drew-formaldehyderesin adhesives; are catalyzed by acid? or acid-producing salts such";fors'example, as ammonium chloride; ammonium sulfate;zammoniumrbiborate,sodium bisulfat'e; andithe like Such'l catalysts: cause the-urea-:formaldehyde reactionzto' proceed" to: an insolubl'e state by bringingabout the CUIiIlg Ofthe r-esiii Wheniureaeformaldehyde type resins aresimultaneously catalyzed and: extended with: a gluten containing rseed'flour; sodium: thiosulfate': is=prefferaiil y employed as the: thinningagent :b ecaus'e sulfur: dioxide: is: formed by the interaction: of thesodium thiosulfate and the" acid produoed% by the interaction of the.urea-formaldehyde resiirand' catalyst. Experimentally; it has beenfound" that quantities-as littleas: 1 part. of so dium: tl'iiosulf'atewill produce" a pronounced thinning and smoothing effect: on I00 partsor" aaaurea -formaldehyde resin: extended with as: much as 400 parts:of' a.- glutemcontaihing;seed? flour: mix:

Catalyst compositions, such as. catalyst1A, and catalyst Bi" shown:below are satisfactory for: use with: a. ureaeforma'ldehydei resinliquid-I containing approximately 62 per cent solids. Prefrahl'ygi. 1.0:parts oi; thescatalyst composition are used for each 100 parts of liquidresin. The catalyst A compositionis preferably used when the;- adhesiveis.- used in.- oold-pressing f; e., room temperature, operations. The;catalyst.- B composition-is. preferably used. when the adhesive isemployed in hot-pressing operations.

' Harts by, weight Ammonium chloride Urea 18.02 Zinc stearate 0.90Sodium thiosulfate 9.01

Catalyst *B 6%. agent: Such; gluten-modifying. agents comprise sulfurdioxide, sulfurous acid, sodium;bisulfite;=. and oth'ermo'difyingsa'gents :ofiv theiclasszdescribedi which readily producessulfur-dioxide; especially;

' those which. produce: sulfur dioxide hy. hydrole jthe acid being'usedin such instancesolely fen-re leasing the S62 Q'ficourse; sulfurdioxide -gasmay be passed into" water and the acidulated Water used tomodifY-theextendier before mix-ing:

withthemelamineresin;

general, sulfur dioxide gas" within the range of= from=0=01tobkOpartsSOz per-100 parts'ofseed flour" givesa satisfactory adhesivecomposition. 7' having good spreading prop'erti'esa Compoundswhioh'readiiy'yi'eld sulfur dioxide by hydrolysis or decompositionmay beused within the range of from 0i'5 -to 10' parts per-"100 parts-of glutencontaining seed flour. used in theresin-seed flour mix-.- Whensodium thiosulfateis used with a urea-formaldehyde type resin,theactualamount of sulfur dioxide formed. from; it depends on and isvdirectly proportional to the amount of acid whichds available todecompose the sodiumthio sulfate:

The usable lifeof a-"hot-press resin formulation isgeneraIly'desiredto-be 24 hours o r lo nger, and this-long life ispbt'ained in some-"casesby buffe1"- ii g the catalyst ccmposit-ion-where anacid-produ'cingcatalyst is-=usedi The: usable life-ore: highly"extendedadhesive composition is iircreased by-the useofa modifyingagentbecause" the mix containing a" modifying agent "has" a smoothfliiidnature up; to th'e timeof "solidifica tion; i although the" liquidlife may"-'actua-1ly"not* be prolonged? When-sucham agent is not used;the

adhesive mix-becomes thick and 'mush like in'a" Parts by weight Ammoniumchloride 27.27 Ammonium biborate 27.27 Urea 36.37 Sodium thiosulfate9.09

, Paraformaldehyde, hexamethylenetetramine, sodium hydroxide,hydrochloric acid, oxalic acid, hypophosphorous acid,paratoluene-sulfonic acid, and the like and combinations thereof may beused as catalysts for the resorcinaldehyde resins and also for somephenol-aldehyde resins. Melamine-aldehyde resins ordinarly do notrequire the use of a catalyst to cure them.

Condensation-type resins which are capable of being brought to aninfusible and insoluble state by methods other than catalysis with anacid:

short time and is low in spreadability due to its high Viscosity.

The gluten-containing seed flour extender may be treated separately witha modifying agent and then added to a condensation-type resin, or themodifying agent may be mixed with the resinextender combination. Theseed flour may be modified in the presence of water, dried, and used 1as an extender when desired. When a resin havproducing catalyst may beextended with gluten-. v

.7 5 ture.

ing a high pH, within the range of from 7.510.0, is used, the action ofthe modifier on the flour gluten is repressed by the base present and itis therefore necessary to add the modifier to the flour-water mix andwait until the desired thinning has taken place before adding the resinto make the finished adhesive mix. Other methods of modifying the glutenwill readily suggest themselves.

The following examples are given for purposes of illustrating theinvention and not by Way of limitation. Unless otherwise stated, allparts givon are by weight.

Example I One mol of phenol was reacted with two mols of 37%formaldehyde to which sufficient caustic soda was added to obtain a pHof 9.5 of the mix- After condensation had been completed,

the water was removed byatomizing the resin in a blast of hot air in adrying chamber to produce a fine phenol-formaldehyde resin powder. Aseparate mix of the extender was then made by adding the modified ryeflour mixture obtained by mixing 100 parts of rye flour with 110 partsof water and 2 parts of sodium hydrosulfite. The extender was then mixedwith 100 parts of the resin powder and 80 parts of water. The mixturethus prepared was used as an adhesive composition for bonding woodveneers at a temperature of 280-300" F.

Example II One mol of urea was reacted with two mols of formaldehyde ata pH of 6.3. After condensing the pH was raised to 7.1 by the additionof trisodium phosphate, and the condensation product concentrated byremoving a part of the water under vacuum until a solids content of 62%was obtained. One hundred parts of the liquid resin was mixed with 100parts of wheat flour, 100 parts of water, 7.2 parts of ammoniumchloride, 1.8 parts of urea, and 0.9 part of sodium thiosulfate.

"The last three ingredients listed may be combined with 0.09 part ofzinc stearate to prevent caking from moisture in the air and used as aone-part catalyst. Ten parts of this catalyst were used. The mixturethus prepared was then used as an adhesive composition for bonding woodat a temperature of 70 F.

Example III Three mols of formaldehyde were reacted with one mol ofmelamine at a pH of 6.1. The condensation product was concentrated undervacuum to a solids of 60%. One hundred parts of the resin were mixedwith 150 parts of wheat flour, 125 parts of water and 1 part of sodiumbisulfite. The mixture thus prepared was .then used as an adhesive forbonding wood veneers in a. hot platen press at a temperature of 280 F.

Plywood made by the use of hot and cold press resin formulationsextended with a seed flour and which contain a sulfur dioxide-producingagent has a strength as measured by a plywood shear test at least equalto or greater than that obtained from an extended adhesive compositionwhich does not contain a. sulfur dioxide-producing salt.

Since certain changes may be made in the above composition of matter anddifferent embodiments of the invention could be made without departingfrom its scope, it is intended that all matter contained in the abovedescription shall be interpreted as illustrative and not in a limitingsense.

It is also to be understood that the following claim is intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:

An adhesive composition of matter consisting of 100 parts of resinpowder obtained by con densing 1 mol of phenol with 2 mols of 37 percent formaldehyde solution in the presence of suiiicient caustic soda togive a pH of approximately 9.5 and thereafter removing the water andpulverizing to produce the dry resin powder; together with parts ofwater and parts of an extender composed of 100 parts of rye flour, partsof water, and 2 parts of sodium hydrosulfite.

LAURENCE E. CLARK, JR.

REFERENCES CITED The. following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,969,347 Bauer Aug. 7, 19342,019,834 Vierling Nov. 5, 1935 2,141,313 Osgood Dec. 27-, 19382,264,732 Weber Dec. 2, 1941 2,302,309 Glarum. et al Nov. 17, 19422,332,801 Leonardson et a1. Oct. 26, 1943 2,333,526 Denyes Nov. 2, 19432,407,599 Auten Sept. 10, 1946 2,492,510 Van Epps Dec. 27, 1949

